1. Field of the Invention
The present invention relates to thermosetting powder coatings. More specifically, the present invention relates to thermosetting powder coatings based on epoxy resins and anhydride curing agents.
2. Description of the Prior Art
Powder coatings comprising epoxy resins and anhydride curing agents are known in the art. The selection of anhydride curing agents and, for that matter, other curing agents is important in obtaining good processing and performance of powder coatings. Generally, polymeric anhydrides have been preferred over their parent polyacids because the former has been found to be more readily miscible. Also, the polymeric anhydrides have generally been found to be lower melting.
By the present invention, polymeric anhydrides have been modified to produce curing agents for powder coatings with substantially improved properties.